1. Field of the Invention
This invention relates to sinusoidal oscillators, and, more particularly, the invention disclosed relates to cost-effective AC excitation of transducers using an integrated electronic circuit package which maintains controlled amplitude of the sinusoidal output of an oscillator circuit with an improved non-linearity correction circuit and a level shifting circuit.
2. Description of the Prior Art
Variable reluctance transducers and certain electrical devices require a highly efficient oscillator capable of producing constant amplitude output signals.
A prior art method used to eliminate non-linearity in transducers included circuitry applying across a net work, which has a non-linear function of variations in the physical parameters, an input signal of such a magnitude that a voltage signal developed across one of the series-connected impedance elements has a predetermined magnitude that is substantially unaffected by either variations in the variable impedance or in the output signal. This prior art technique is further discussed in U.S. Pat. No. 3,837,227 to Tavis.
Another method provided amplitude stability for a sinusoidal oscillator by improving low frequency noise rejection in the control circuit and using a differential amplifier in the negative feed back loop to retain the temperature insensitivity with a very low power consumption. This prior art is discussed in U.S. Pat. No. 4,947,139 to Tavis.